Apparatus for producing reinforced tubing



Feb. 5, 1957 c. A. cAsTELLAN APPARATUS FOR PRODUCING REINFORCED TUBINGFiled July l2, 1955 www u 0\! J M\\\ 7 7- 6 7 g 2 4 Q a w. n i 4 .Il 2 44 Ir r 3 .4 4 4 i 1 4 nted States lhce 2,779,971 Patentedl Feb. 5, 1957APPARATUS FOR PRODUCING REINFORCED TUBENG Carl A. Castellan, DelawareCounty, Pa., assigner to American Viscose Corporation, Philadelphia,Pa., a corporation of Delaware Original application April 14, 1953,Serial No. 343,673, now Patent No. 2,730,761, dated January 17, 1956.gzrguyltgl and this application July 12, 1955, Serial No.

It is the primary object of Ithis invention to provide an limprovedapparatus for forming reinforced flexible tublng in a continuous manner.The invention is par ticularly concerned with the continuous productionof reinforced tubing by the continuous feeding in an axial direction ofa helically coiled reinforcement, such as of wire or plastic, through apassage in a device for extruding around the reinforcement a plasticmaterial adapted to form the Wall of the tube.

In systems heretofore proposed for carrying out lthis type of procedure,the helically coiled reinforcement is fed to the tubing extrusionorifice by a rotary member having a helical groove with-in which thereinforcing helix is received. The rotation of the grooved member causesthe helical reinforcement to adv-ance ax-ially but because of thesliding friction between the helices of the coil and the grooves in therotary member, such axial feeding Imoti-on is accompanied by a severetwisting moment exerted upon the helix. This twisting action extendsfrom the rotary member into and sometimes beyond the ext1usion positionand when released further on, such Itwist tends to distort the wall ofplastic material within which the strained or twisted coil was embeddedat the point of extrusion.

According to the present invention, means is provided for axiallyadvancing the helical reinforcement without the exertion of a twistingmoment upon the coil thereby avoiding the tendency to form a distortedtubular wall in the iinal product. In general, this is accomplished byproviding means for axially advancing the helical reinforcement throughits guiding channel or passage by a device which comprises means forsubstantially positively gripping ya convolution of the coil. Thisgripping means preferably grips the wire yor plastic transversely of itscross-section lt-hereby preventing lengthwise sliding motion of the wireor plastic element of the coil relative to the gripping element orelements.

In the drawing, which is illustrative of the invention,

'Figure 1 is a sectional elevation of the present invention.

As shown in Figure l, the extrusion device 27 is provided with a chamber5, passage 6, annular orifice 7 terminating in the wall Sa of a channel4a. A plastic tube-forming material may be fed to the chamber 5 by meansof a conduit 9 communicating therewith -to which a supply of the plasticmay be connected through a suitable pump diagrammatically shown at lll.The pump 10 is preferably of Ia positive displacement type, such as agear pump, so tha-t the plastic material may be fed to the extrusiondevice at any desired predetermined constant rate. A heating element isshown at 3a. The extrusion head 27 is provided with an annular recess,to the bottom of which an annular internal gear 28 is xedly secured asby screws 29. A thrust bearing or washer 30 is received thereon and abushing 31 is received above the washer 30. A hollow cylinder or sleeve32 is rotatably mounted within the bushing 3l and an outboard bearing 33carried in suitable brackets 35 connected to 2 the extrusion head or.supporting frame therefor. A sprocket 36 is secured `to the cylindricalmember 32 for rotating it. Upon the inside wall of the cylindricalmember 32, a bracket or arm 37 is secured and on this bracket a pair ofrotors 38 and 39 are mounted on the shafts 40 and 41. As shown, theshaft 41 may extend through an outer arm 42 extending from the bracket37. The outboard end of shaft `40 carries a gear 43 which is in meshwith the annular gear 28. The rotors 38 and 39 preferably haveconcavely-curved peripheries adapted to embrace the wire 44. lf desired,the periphen'es of these rotors may be of rubber yto provide bettergripping action. An additional sleeve 45 may be secured within thecylinder 32 to provide an internal guiding wall 46 of the same diameteras the wall 8a .to serve as a guide for the helical reinforcementproceeding to the gripper device compri-sing rotors 38 and 39. Anannular groove 47 may be provided to catch any oil draining from thering gear 23 and a bore y48 extending through the extrusion head walldirects such oil Ito a collecting vessel y49 secured to the outer wallfrom which it c-an be readily removed.

The extrusion system of Figure 1 may receive the reinforcing coil from asupply receptacle and discharge the extruded tube to supporting andadvancing systems and into a collecting device of 'any suitable andconvenient construction. If needed, coagulating means, such as jets ofcool iluid, may be played against the tubing as it leaves the extrusionsystem.

In the operati-on of the system, the size of gears 28 and 43 are socorrelated with respect to the diameter of the driven roll 38 as tocause linear advance of wire 44 by the rolls 3S and 39 a distance equalto the length of one coil of the helix duri-ng Ia single revolution ofthe member 32. The angle yof helix being herein dened as the anglebetween the tangent to the helix and the generatrix of the cylinderwithin which the helix is located. in other words, the rotary means 38and Y39 is driven at a rate to feed the element of the helix `at a ratesubstantially equal to the quotient obtained by dividing the rate ofrotation of the point of engagement between the element and the rotarymeans about the axis of the channel by the sine -of the helix angle.When. so constructed, there is no twisting component imparted to thehelix but it is advanced a -single pitch of the reinforcement coilduring one revolution of the cylindrical member 32 and such advance isstrictly uniform and in an axial direction. This strict axial motionresul-ts because the axis of shaft 4d lies in a plane which is parallelIto the axis ofthe channel 4a lbut inclined out of parallel to such axisby an angle complementary yto the angle of helix and the rot-ation ofcylinder 32 yabout the axis of the channel 4a causes the point ofgripping between the wire 44 and Ithe nip rolls 38 and 39 to move in aplane.` that is at right angles to the laxis of the channel 4a.

While -t'he device is disposed -to discharge the extruded tubingdownwardly, it may be disposed. to discharge it vertically upwardly orat any inclination to the vertical including a generally horizontaldirect-ion. However, the action of gravity favors the dispositions shownand less diiculty is encountered in producing tubing of substantiallyuniform wall thickness with this arrangement. The system of yFigure 1 isparticularly adapted to produce the larger sizes of cylindricallreinforced tubing.

The system of the present invention is adapted to produce reinforcedtubing in la continuous manner from all sorts of plastic materials, suchas vinyl resins, thermosetting resins, elastomeric polymers such asrubber, syn- -thetic rubbers or the like, polyethylene, nylon, cellulosesolutions and derivatives, such as solutions of cellulose esters involatile solvents, including cellulose acetate, also cellulose ethers,such as ethyl cellulose, hydroxyethyl cellulose and ca'rboxymethylcellulose. The helical reinforcement may be formed of a wire of metallicor plastic material. It is preferably highly resilient so as to allowbending `of the nal tube when the Walls thereof are of a flexiblematerial yor elastic material.

It is to beunderstood that `changes and variations may be made Withoutdeparting from lthe spirit and scope ot the invention -as dened in theappended claims.

`I claim:

l. Apparatus f'or producing reinforced tubing cornprising `an extrusiondevice, `an internal wall in the device de'ning a channel for receivingand guiding a fcoiled reinforcement element through the device, a `di-s-`charge for-ice extending circumferenti'aily of the Wall, rotary meansadjacent Vthe Wall for positively gripping the element, a rotatablesupport for the rotary means,

means for rotating the lsupport about the axis of the channel, and meansfor driving the rotary means to feed the element therethrough at a ratesubstantially equal to the r-ate of Irotation of the point `ofengagement between the element and the rotary means about the axis ofthe channel divided by the sine of the helix angle.

2. Apparatus as defined in claim l in which the.

rotary means icomprises a pair of nip rolls for engaging l0 the elementand the means for driving .the rotary means comprises `a `fixed annulargear 'and a pinion in mesh therewith connected to `one of lthe nip rollsto rotate it.

No references cited.

